1. Field of the Invention
The present invention relates to a nitric acid-based salt granule comprising a nitrate or nitrite, and an aggregate thereof.
2. Background Art Relating to the Invention
Nitric acid-based salts, such as nitrates (e.g., potassium nitrate, sodium nitrate, ammonium nitrate, calcium nitrate, etc.), nitrites (e.g., potassium nitrite, sodium nitrite, ammonium nitrite, calcium nitrite, etc.) and hydrates thereof are important as nitrogenous fertilizers. In addition, they are widely used as salt bath materials, gunpowder materials, fireworks materials, dye materials, chemical material, and the like.
Recently, fused potassium nitrate has been used as an ion exchanger for chemical reinforcement of glass. In particular, this kind of a nitric acid-based salt has been used in the art of optical fiber.
The nitric acid-based salts are designated as dangerous substances. Thus, serious attention should be paid to handling of the nitric acid-based salts during production, transportation and storage.
Accordingly, it has been known that nitric acid-based salts are stored in the shape of a granule rather than in the shape of a powder. For example, JP-A-7-109112 discloses the formation of a nitric acid mixture in a disk-shape tablet, a semicylindrical granule or a cylindrical granule.
However, a nitric acid-based salt granule having such a shape has the following disadvantages during transportation and the like.
In other words, in order to use nitric acid-based salt granules, the granules are not took out one by one for transportation. Instead, some amount (large number) of the granules are aggregated for handling. Industrially, the aggregates from the storage warehouse are piled up on a belt conveyor, and then conveyed to various facilities.
However, since the transportation on a conveyor or the like is vibrated, the aggregates of granules molded in the conventional shape such as a disk-shape tablet are easy to get out of the shape piled up on the conveyor belt (easily break into constituent granules) and fall from the conveyor belt. In particular, the aggregates of granules in the shape of a disk-shape tablet or a cylinder granule are easy to break into constituent granules and fall from the belt, which markedly causes the above problem.
Furthermore, while the aggregates are stored, the lower part of the aggregates is subject to a load of the own weight of the aggregates accumulated thereon and thus is easy to crush. When the granules thus break, the positive efforts of molding the nitric acid-based salt compound into a granule become meaningless. It has thus been desired to provide a nitric acid-based salt granule which is hard to break.
Therefore, an object of the present invention to provide a nitric acid-based salt granule which is hard to roll over when it is used alone, and which is hard to landslide when it is used as an aggregate.
Another object of the present invention is to provide a nitric acid-based salt granule having a shape which is hard to break.
These and other objects of the present invention have been accomplished by a granule of a compound comprising a nitrate or nitrite, wherein a part of the body of the granule has a protrusion.
Furthermore, these and other objects of the present invention have been accomplished by a granule of a compound comprising a nitrate or nitrite, wherein the compound is compressed so that:
the body of the granule is substantially hemispherical or substantially spherical;
the body of the granule is rimmed with a protrusion toward the diameter direction on the periphery of the body of the granule; and
the body and the protrusion are integrally molded.
Moreover, these and other objects of the present invention have been accomplished by an aggregate of the above granules.